Obesity and diabetes are more common in African-Americans than whites. Because free fatty acids (FFA) participate in the development of these conditions, studying race differences in the regulation of FFA and glucose by insulin is essential. Background: Quantitative evaluation of insulin regulation on plasma glucose and free fatty acid (FFA) in response to external glucose challenge is clinically important to assess the development of insulin resistance. Mathematical minimal models (MMs) based on insulin modified frequently-sampled intravenous glucose tolerance tests (IM-FSIGT) are widely applied to ascertain an insulin sensitivity index. However, the action of insulin on FFA kinetics is not considered in most MMs. Neither glucose clamps nor IM-FSIGT are normal physiological conditions so it is important to quantify insulin modulation of glucose and FFA metabolism in postprandial state. Methods: Assessing post-prandial insulin secretion rate and insulin clearance in Dr. Sumner's Federal Womens cohort. Recruitment is going well and Dr. Chung indicates that they will complete data collection on 55 of the 66 women by the end of May 2016. This is an important study to identify the causes of postprandial hyperinsulinemia in women of African descent. We are also working with Dr. Sumner's group in analyzing Vitamin D levels in connection with bone density and thyroid hormone.